Familial inheritance and screening of first-degree relatives in common variable immunodeficiency and immunoglobulin A deficiency patients.

Common variable immunodeficiency (CVID) and immunoglobulin A deficiency (IgAD) are the most prevalent primary immunodeficiency disorders. High rates of familial inheritance have been described in CVID and IgAD, but it is unknown in different ethnic populations. We aimed to determine the prevalence of familial cases and whether they showed more severe clinical characteristics than sporadic ones in Turkish patients. A total of 40 CVID and 70 IgAD patients and their 251 first-degree relatives (FDRs) were evaluated. Demographic, clinical, and laboratory data were reviewed. A familial case was defined as a patient with at least one affected FDR (A-FDR). The rate of parental consanguinity was 19.1%. There were 37 familial cases (37/110) (33.6%) with at least one A-FDR. There were 48 A-FDRs who had immunoglobulins lower than age-related normals (48/251) (19.1%). Pulmonary infections were significantly higher in familial cases. To our knowledge, this study includes the highest number of CVID/IgAD patients and their FDRs in literature. Familial cases are at least 30% of the IgAD and CVID patients, and they have more frequent lower respiratory tract infections than sporadic ones, so these patients have to be evaluated depending on their being familial or sporadic for better management. The risk of carrying any immunologic alterations in relatives of patients with IgAD and CVID is approximately 20%. Although most A-FDRs are asymptomatic, considering the risk of progression to CVID by age, we highly recommend routine screening for FDRs.